Core vs domain kit boundary

This subject has provenance in frozen ADR history (0014-core-vs-domain-kit-boundary.md) but no living decision has been ratified yet under the topic-keyed decision registry (context/contracts/decision-registry-contract.md). This stub records that the subject is open and links the frozen ADR(s) as provenance; it is not a decision.

When a living decision is ratified for core vs domain kit boundary, update this file’s status to current, add rationale, and keep the adr evidence links as provenance for the history that led here.